In recent years, the practical use of the directed self-assembly lithography technique utilizing a property that a block copolymer is self-assembled is discussed (for example, Patent Documents 1 and 2 and Non-Patent Document 1). In the directed self-assembly lithography technique, first, for example, a solution of a block copolymer containing an A polymer chain and a B polymer chain is applied to a substrate. Then, when the substrate is heated, the A polymer chain and the B polymer chain mutually randomly solid-dissolve undergo phase separation to form A polymer regions and B polymer regions which are regularly arrayed. Then, patterning the block copolymer is performed by removing either the A polymer regions or the B polymer regions, thereby forming a mask having a predetermined pattern.